From 7e7e648fa8a3a345e3f8ad7d375b381b5d62e270 Mon Sep 17 00:00:00 2001
From: Marco Thomas <github@marcothms.de>
Date: Tue, 17 Jun 2025 10:54:42 +0900
Subject: [PATCH] fix(interpreter): wrong le byte order on pop

---
 src/interpreter/computer.rs | 15 ++++++++++++++-
 src/interpreter/memory.rs   |  2 +-
 src/interpreter/register.rs |  4 ++--
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/interpreter/computer.rs b/src/interpreter/computer.rs
index 28af901..cff82e6 100644
--- a/src/interpreter/computer.rs
+++ b/src/interpreter/computer.rs
@@ -257,5 +257,18 @@ impl fmt::Display for Computer {
 
 #[cfg(test)]
 mod tests {
-    // use super::*;
+
+    use super::*;
+
+    #[test]
+    fn test_push() {
+        let mut c = Computer::new();
+        let val = ImmediateOperand::Word(0x1234);
+        c.push_stack(val).unwrap();
+
+        let target = PopTarget::Register(crate::register::Register::AX);
+        c.pop_stack(target).unwrap();
+
+        assert_eq!(val, c.regs.read(crate::register::Register::AX))
+    }
 }
diff --git a/src/interpreter/memory.rs b/src/interpreter/memory.rs
index 2406a5a..460d68f 100644
--- a/src/interpreter/memory.rs
+++ b/src/interpreter/memory.rs
@@ -38,7 +38,7 @@ impl Memory {
             .get((idx + 1) as usize)
             .ok_or(InterpreterError::MemoryOutOfBound(idx))?
             .to_owned();
-        Ok(Word::from_be_bytes([b1, b2]))
+        Ok(Word::from_be_bytes([b2, b1]))
     }
 
     /// Write an [`ImmediateOperand`] to a memory location indexed by a [`MemoryIndex`].
diff --git a/src/interpreter/register.rs b/src/interpreter/register.rs
index 025fe6e..857fd33 100644
--- a/src/interpreter/register.rs
+++ b/src/interpreter/register.rs
@@ -31,7 +31,7 @@ impl Register {
 
     /// Decrement stack pointer
     pub fn push(&mut self) -> Result<(), InterpreterError> {
-        if self.sp <= 2 {
+        if self.sp < 2 {
             return Err(InterpreterError::InvalidRegisterState(*self));
         } else {
             self.sp -= 2;
@@ -41,7 +41,7 @@ impl Register {
 
     /// Increment stack pointer
     pub fn pop(&mut self) -> Result<(), InterpreterError> {
-        if self.sp >= 0xffff - 2 {
+        if self.sp > 0xffff - 2 {
             return Err(InterpreterError::InvalidRegisterState(*self));
         } else {
             self.sp += 2;